Multiculture of native species in irrigation ponds in central Mexico

A Moctezuma Malagón, G de la Lanza Espino*, C González-Rebeles Islas** and C González Esquivel***

Universidad Autónoma del Estado de México, Instituto Literario Ote. 100, Toluca, México, México 50000
moctezuma444@yahoo.com.mx
*Instituto de Biología and **Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México,
Ciudad Universitaria, México, D.F. México 04510
***Centro de Investigación en Ciencias Agropecuarias, Universidad Autónoma del Estado de México, Instituto Literario Ote.
100, Toluca, México, MÉXICO 50000
cge1@uaemex.mx

Abstract

Production systems based on native species are alternatives for extensive production, better fit to environmental, social and economic local conditions. Rational use of resources must encompass the community as a whole, under a double scope of use and conservation. To assess this, an experimental native species multiculture was established over a two-year period in irrigation ponds, aiming at the recovery of natural communities, through experimental breeding of some species that show evident productive potential. Cultures were organized under five groups.

Orchards: plantations of water yam (Sagittaria latifolia), water cress (Hydrocotyle ranunculoides) and spade (Typha latifolia) were successful. Invertebrates: potentially productive species were identified and those currently harvested, crayfish Cambarellus montezumae) and water fly (Consella mercenaria), were evaluated. Fish: small whitefish (Chirostoma riojai) capture, transport and (re)introduction were efficiently achieved. Amphibians: leopard frog (Rana spectabilis) was raised in tanks and small pond, with little success. Waterfowl: resident population of Mexican duck (Anas diazi) was evaluated, collected eggs were incubated, ducklings bred and nested successfully in captivity. Present use and marketing of these species is described. The experiments support the hypothesis that the culture and utilization of native species evaluated is technically and economically feasible.

Keywords: irrigation ponds, multiculture, native species, resource management

Policultivo de especies autóctonas en estanques de riego en el centro de México

Resumen

Los sistemas de producción basados en el uso de especies nativas son opciones para la producción semiextensiva, que pueden ensamblar adecuadamente en el marco social, económico y ambiental. La utilización racional de estos recursos debe partir del manejo de la comunidad como un todo, bajo los puntos de vista de aprovechamiento y conservación. El objetivo de este estudio fue establecer un sistema de policultivo piloto de especies autóctonas, en un ambiente natural semiextensivo en estanques de riego, mediante ensayos para evaluar la crianza de algunas especies con potencial productivo. El cultivo experimental se estructuró en cinco líneas:

Anaticultura: se evaluó la población residente del pato mexicano Anas diazi y se logró su incubación, crianza y anidación en cautiverio. Ranicultura: se cultivó rana leopardo Rana spectabilis en piletas y se introdujo a los estanques. Piscicultura: se logró el transporte y reintroducción del charal Chirostoma riojai. Recolección de invertebrados: se identificaron especies con potencial productivo, evaluando al acocil Cambarellus montezumae y al mosco de agua Consella mercenaria. Horticultura: se desarrollaron los cultivos de: papa de agua Sagittaria latifolia, berro Hydrocotyle ranunculoides y tule Typha latifolia. Se describe el uso actual y comercialización de estas especies. Los ensayos mostraron que el cultivo y utilización de la mayoría de las especies evaluadas es técnica y económicamente factible.

Palabras Clave: aprovechamiento de vida silvestre, bordos de riego, manejo de recursos, policultivo

Policultivo de espécies autóctones em tanques de irrigaçao no México central

Resumo

Os sistemas de produção baseados no uso de espécies nativas são opções para a produção semi-extensiva, podem unir adequadamente os contextos social, econômico e ambiental. A utilização racional destes recursos deve partir do manejo da comunidade como um todo, sob os pontos de vista de aproveitamento e conservação.

O objetivo deste estudo foi estabelecer um sistema de policultivo piloto de espécies autóctones em um ambiente natural semi-extensivo em tanques de irrigação, mediante experimentos para avaliar a criação de algumas espécies com potencial produtivo. O cultivo experimental foi estruturado em cinco linhas, são elas: Anaticultura: avaliou-se a população residente do pato mexicano Anas diazi e realizou-se sua incubação, criação e adaptação em cativeiro. Ranicultura: cultivou-se rã-leopardo Rana spectabilis em bandejas e depois estas foram introduzidas nos tanques. Piscicultura: realizou-se o transporte e a reintrodução do charal (peixe das lagoas do Estado de México, no México) Chirostoma riojai. Coleta de invertebrados: foram identificadas espécies com potencial produtivo, avaliando a lagosta anã Cambarellus montezumae e a mosca d'águaConsella mercenaria. Horticultura: desenvolveram-se os cultivos de: batata d'água Sagittaria latifolia, agrião Hydrocotyle ranunculoides e tabua Typha latifolia. Descreveu-se o uso atual e comercialização destas espécies. Os experimentos mostraram que o cultivo e a utilização da maioria das espécies avaliadas é técnica e economicamente factível.

Palavras-Chaves: aproveitamento de vida silvestre, barragens de irrigação, manejo de recursos, policultivo

Introduction

Traditional natural resource management systems use a large number of local species under extensive multicultural production systems. This diversity is progressively lost by the replacement of local species by foreign ones (Blackburn et al 1999). Introduced species have a negative impact on local species, therefore decreasing stability of natural systems (Arredondo 1983; Weber 1993). Some authors refer to a synergic action of local and exotic species, although it is evident that resource demand of the latter has an impact on the former, if niches overlap. Domestic species are bred in artificial environments, since in most cases they have lost their ability to survive in natural environments, increasing the need for labor and other inputs (Grandin 1998).

These premises make evident the need to evaluate culture techniques and species, since many current practices are harmful or at least obsolete. It is a paradox that there is recent interest in the conservation of local breeds as gene banks (Scherf 1997), in animals (Drucker and Anderson 1999) as well as in domestic plants (Arias et al 1999). In contrast, the interest in native species is scarce (Scherf 1997), even though they form a greater reserve in terms of diversity and adaptability. There have been recent attempts to revaluate traditionally used species, that dominant "modern" development has ignored (Ojasti 1993, Chardonnet et al 1998, Olguín et al 1999). Local species breeding allows a reduction of the negative effects of limiting factors. These species are adapted to local environments, since they evolved in situ, as it was demonstrated on drylands (Hopcraft 1980). This principle may be applied to wetlands, thus contributing to their conservation.

Rational use of resources involves the management of a natural community as a whole (Altieri 1994), there relationships between biotic and non-biotic elements is maintained, to insure system homeostasis. Ideally, as many species as present in the ecosystem should be exploited. This is obviously limited by complex harvesting procedures, a constraint that could be overcome with appropriate management techniques.

Production systems including wild species pose alternatives to mass production better fit to the social frame they co-evolved with (Toledo 1995), thus they deserve a social evaluation to justify its value (Bailey 1984), coupled with productive (sustained yield) and environmental indicators (Savidge and Scott 1980). The need of basic and methodological research has been stressed by representatives of the Mexican government (Carabias 1999).

As a systemic approach, agroecological theory is based on two methodological focuses: the description and analysis of present production systems, through the observation of typical situations in specific environments; and experimentation with alternative systems (Morales 1980, Olguín et al 1999), that can be inserted harmoniously to complement and eventually substitute inadequate management procedures.

Among the most common problems of wetlands are volume loss and pollution (Goldsmith 1998). Their recovery is urgent since they are restricted to border areas between dry and deep water areas, which are preferred areas for human settlements. Research about these ecosystems in general does not offer evaluation mechanisms for utilization projects (Bojórquez 1996, Toledo 1998). For wetland management in particular, a formal sustainability evaluation is required. The choice of management techniques must consider present and future use planned by producers, besides current environmental state of each reservoir, since they are unique (Roggeri 1995, Cervantes 1996).

The objective of this study was the establishment of cultures under a semi-extensive system of some native species, in irrigation ponds at the Lerma River Basin in Central Mexico, as an alternative to common carp (Ciprinus carpio) monoculture, which is widely promoted by state agencies in the region. Ponds are filled during the rainy season (June-October), and emptied (partially or totally) at the start of the maize crops (March-April). The specific aims were: experimental breeding of some native species in a critical survival situation or with evident production potential, and the economical comparison with species in present use.

Material and methods

Irrigation ponds involved in this experiment are part of the high Lerma River basin, located between 19° 22' 30" and 19° 06' 30" N and between 99° 28' 00" and 99° 32' 30" W. The basin extension is 5,354 km², its average altitude 2600 masl, average rainfall 800 mm, meaning 4,283 Mm³ a year. Climate is sub-humid, temperate with summer rains, average temperature of 12 to18 °C (SPP 1981). The surrounding vegetation is mainly maize crops (CCRECRL 1993). As this is an important water source for the Toluca and Mexico City valleys, recovery of this basin is considered a priority (Arriaga et al 1998). The main problem is a reduction in the volume and flooded area, as has happened with much large hydraulic infrastructure (Goldsmith 1998). The area is under agricultural use, and more recently evolved into urban and industrial use, which provoked eutrofization and poisoning of the main stream. Irrigation ponds are supplied by rain and small creeks, remaining more or less free from industrial pollution, so they allow a chance to experiment alternative management procedures.

Tests were performed in 2001 and 2002 at "Las Maravillas", a pond owned by the Universidad Autónoma del Estado de México, and "Santa Rosa", a pond owned communally by campesino farmers. The domestication process implied several steps: knowledge of the biology of each species, the provision of an adequate feed source and reproduction facilities, in order to establish basic breeding techniques; and stabilization of harvesting and commercialization processes.

Experiments performed with five groups of species are described next. Feeding and reproduction techniques used were previously evaluated. Present or potential prices of so me byproducts were estimated, through enquiries to producers and at local markets.

Horticulture

Among the species used at present are water cress (Hidrocotyle ranunculoides L.f.) and water yam (Sagittaria latifolia Willd). For this experiment three parcels in each pond were planted, 10 plants per m². Density and biomass was estimated in the wild vegetation. For water yam 150 tubers were planted in each pond in February and an equal amount in April, in order to compare survival rates in winter or spring. Water depth for planting was between 20 and 50 cm (Garbisch and McLinch 1994). Some were left on the bottom and others buried 5cm, planting density was 10 tubers per m², as suggested by Zepeda (2001). Twenty additional tubers were planted in a plastic container, and natural density and harvesting time were evaluated. Since it is abundant, Lemna gibba L. was not planted, but used as forage for ducks. Spade (Typha latifolia L.), besides providing a microhabitat for other species, is important as a traditional weaving material for mats (petates) and as a basis for floating orchards (chinampas). It has good potential use as thermal insulation for houses. Natural density and biomass were evaluated. In order to initiate formal culture, spade was planted in bunches, or individually to ease handling (Harris and Marshall 1963).

Invertebrate digging

Crayfish (Cambarellus montezumae Saussure 1857) is harvested and sold locally (Moctezuma 1996). Water fly (Consella mercenaria Say hemiptera) is abundant in some ponds, and is used as a protein source for song birds. Netting is done with spoon nets (maclas) according to traditional design. Reproduction of both species was kept natural, and capture effort evaluated. Other useful arthropod species were identified for further evaluation.

Fish culture

Small whitefish (Chirostoma riojai Solórzano and López 1965 aterinidae) is endemic to Toluca valley, its fisheries have been described by Méndez (1996, 1999). For this experiment 4,700 fish were captured, transported, and introduced, one half in each experimental pond. Because of their sensitivity to handling, fish were captured with 3mm mesh nets to prevent damage to branchiae, air exposure for more than 15s was avoided. They were then transported in plastic bags with oxygen and salt to reduce stress due to ionic imbalance. Adequate water levels were kept, for brood protection vegetation is required. Besides, 200 organisms were placed in a 10 m³ concrete container, fed only with plankton growing spontaneously in the container.

Frog culture

Leopard frog Rana spectabilis Hillis and Frost 1985 (Rana pipiens) has a local use as food, though it is smaller than foreign bull frog (Rana catesbeiana), also bred locally. 2000 tadpoles were placed in each pond, their nutrition during the first development stages was based on natural invertebrate production. To observe the growth phase in captivity another 200 tadpoles were placed in a 15 m³ concrete container and an equal amount in shallow (10 cm) concrete containers, fed with chicken feed and water fleas (Daphnia spp.). By the end of the season populations in ponds were evaluated using 150m transects. Commercialization of meat and pelts were described.

Duck culture

Mexican duck (Anas diazi Ridgway 1886) is one of the few year-round resident species. Considering its size, is a potential meat source, and given its genetic proximity to domestic collar duck (Anas platyrynchos L.) both species were evaluated. Breeding behavior of the wild population of Anas diazi in Las Maravillas was measured in terms of number of pairs, number of nests and number of eggs per nest, throughout the season, lasting from February to November. From natural nests, 20 eggs were collected and incubated artificially. At birth, ducklings were placed in a breeder and fed with commercial chicken food, and were mixed with 15 Anas platyrynchos chicks to compare them for development and tameness, all were dewormed and vaccinated. At five weeks old the ducklings were moved to a four m² enclosure with a 50 m² partly flooded pen adjacent to Las Maravillas. Maize was provided as supplementary feed and growth was evaluated. Anas platyrynchos ducklings were also provided to cooperating farmers living next to Santa Rosa. Fat proportion in both species was compared.

Basic physical and chemical parameters were monitored weekly in order to evaluate and control water quality,

Results

Horticulture

Water cress Hidrocotyle ranunculoides planted in winter rooted well, growing both tall and wide. An average of 1000 plants per m² was calculated corresponding to a biomass of one kg/m² (stems and leaves being the edible portion). This vegetable is still currently eaten, but price was not defined since local commerce has almost disappeared, because consumers are aware of dubious sanitary quality.

Water yam Sagittaria latifolia tubers planted by the end of winter were 10% successful, so this species was established in other ponds, but most roots were dragged towards deep water when flowed for irrigation. These results indicate that it is necessary to keep water levels under 0.5m, and bury the root just enough to avoid floating. Competing vegetation should be eliminated. Tubers planted in the ponds in summer had leaves after 10 days; they grew 30% less than those kept in plastic containers, but they were darker and stronger. In wild vegetation, densities of 20 to 70 plants per m² were recorded. Yields are up to 10 tubers per plant weighting 5g each. In two hours of work 200 pieces can be harvested, by removing the bottom with forks and picking yams when floating. The growing season goes from November to April. This vegetable is sold locally at US $0.10 a piece. Spade Typha latifolia transplants of individual plants were not successful since they float and can not be kept vertical. On the other hand, bulks were easily rooted. At Las Maravillas, spade covers 30% of the surface, with an average density of 24 stalks per m² and green biomass of 8.5 kg/m², which means twice the amount reported by Mitsch et al (1991), (not considering stalk freshness). In some cases insect larvae destroy the xilema of a few stalks, while others are spotted, diminishing product quality. Spade is soId in the streets by artisans who build and repair chairs, price is US$3 to US$10 each according to mesh complexity (a person can weave up to six per day). Artcraft from several species of spade are exported to the United States, and at present fresh material is imported from the neighboring Michoacan State, so commercial culture may be profitable.

Invertebrates

In new ponds crayfish Cambarellus montezumae and water fly Consella mercenaria are captured year round, being both abundant species, reproduction is suggested to be kept by natural mechanisms. Cooked crayfish price is US$4 per kg. Fisherwomen obtain three to four kilograms in a morning of fishing, it is sold in local markets, but most of it is for self consumption. If there are no ducks, four to five kilos can be obtained in four hours. The price of adult water fly for bird food is US$8 per kg, in Mexico City eggs (ahuahutli) are sold at US$6 per kg, though these are not harvested in the study area. Another two edible species were identified: dragonfly nymphs Anax. sp. (Odonata Aeschnidae) common but not abundant, and water fleas Daphnia spp. and Moina spp., important as food for some fish (Ramos 2000).

Fish culture

Whitefish Chirostoma riojai relocated survival was 95% in concrete containers, after one year they remained alive feeding on spontaneous green algae, but reproduction was not observed. Only two specimens were recovered at Las Maravillas, where predators are abundant. Required larger nets were not available. An obvious limiting factor for culture is keeping adequate water quality and volume, since ponds do not have precise irrigation programs. At present, this fish is captured from February through September in a nearby dam and in ponds, for self consumption and small scale trade. Beach drag nets and spoon nets are used with this purpose, and about eight kg per day are obtained. The direct, fishermen-to-consumer price is US$ 2 per kg (US$ 3 in markets).

Frog culture

Metamorphosis in the 15m³ concrete container was 75%, and 50% in 1 m³ containers. About 80% of the tadpoles already in metamorphosis died when moved. At Santa Rosa, about 300 adults were estimated, equivalent to 15% of those introduced. Abundant vegetation prevented accurate measurement in Las Maravillas. The most important causes of loss were probably migration, aggravated by habitat fragmentation and predation by white crane (Bubulcus ibis L.), which became abundant during the last five years. Local frog price is US $10 per dozen and as pets up to US $5 a piece, whilst the international price for legs is US $3 per kg. Only one specimen of axolotl (Ambystoma spp.). was recorded at Las Maravillas, and none at Santa Rosa. There is at least one menaced endemic species, Ambystoma lermensis. These species are sold locally at US $8 per kg (Pérez and Martínez 1999).

Duck culture

The wild population of Anas diazi under study shares the area with seven migrating species, population estimates yielded the following results: 27 pairs (two per hectare), 14 nests per season (June to October), with an average 6.5 eggs per nest. Eggs collected and artificially incubated all hatched. Chicks became sick (probably by viruses), and one of each species died. To determine meat yield, growth was registered at five months of age. Anas diazi had an average total length of 54 cm and an average weight of 840 g, wheras Anas platyrhynchos ducks measured 71 cm and weighed 2320 g in average.

Courtship behavior and nesting were recorded on both species: Since Anas diazi pairs are territorial, natural incubation in captivity is difficult. Anas diazi breeding could therefore be an economically profitable option, as pets are priced at US$3 per duckling and US$20 per adult. As a meat producer it has the advantage that only 16% of live weight is fat, as compared to 28% in Anas Platyrrynchos. Ducklings from Anas Platyrrynchos bred at Santa Rosa had a 90% survival rate when slaughtered. The duck meat market is profitable, as imported duck sells for US$4.5 per kg, but supply is irregular. Feather commerce requires breeders organization, since special feathering machinery is required. Coot (Fulica sp.) is a resident species eaten regionally, and ruddy duck (Oxyura jamaicensis L.) is attractive as a pet. Therefore, specific evaluations of these species are required.

Discussion

Results obtained with each species are specific about the limiting factors involved and the possibilities of controlling them (Table 1).

In the case of orchards, planting and harvesting procedures are linked to seasonal variation in water volume. Therefore, it is a priority to determine ideal depth for each species, in addition to the programming of location and the planting date, according to an irrigation schedule (Sculpthorpe 1967). If this is achieved and pollution is eliminated, water orchard production can be simple. For spade Typha latifolia, depth control is also important along with fire control. The division of land using channels can reduce this problem and improve border effects. The productivity for this species appears to be high in this experiment, since previous data were 25 to 30 ton/ha (Mitsch et al 1991), although water content was not specified. Market shows an excellent perspective for this species.

Intensive crayfish Cambarellus montezumae culture is feasible, since commercial food is readily accepted, but up to date it is not profitable. Seasonal pond breeding is better, using natural productivity, than intensive production (Moctezuma 1996). Cultures of crayfish and water fly Consella mercenaria are easy, but fishing equipment (net type) must be changed and the trade system organized to avoid dumping. For whitefish, pollution is also the main limiting factor in experimental ponds. Very low oxygen concentrations were recorded (under 2 ppm), but fish resisted without apparent suffering. Fisheries at nearby Cuitzeo lake get 680 kg/ha of this genera Chirostoma spp, and are considered important, since these species grow fast and reproduce all year round (De la Lanza and García 2002). These species help to keep high oxygen concentrations by eating zooplankton. As compared to common carp (Ciprinus carpio) monoculture, usually bred in these ponds, this species yields only 466 kg/ha (Rosas 1976) and present retail price is only US$ 1.6 per kg. However, the main problem with carp culture is its incompatibility with native species multicultures. As a carnivorous, it predates on whitefish, and by removing the bottom of the ponds, decreases oxygen concentrations.

For leopard frog Rana spectabilis the limiting factor is habitat fragmentation. The design of protected areas of sufficient size is not feasible, due to regional urban development. Although performance was low in irrigation ponds, breeding is possible, but in smaller, privately owned ditches, where predators and migration may be controlled. A previous report indicated that wild population harvesting is not sustainable (Edwards 1990).

Mexican duck Anas diazi breeding is very profitable. Incubation and breeding processes implied more labor and expenses related to required equipment, but increased survival compensates this. The meat yield is 68 to 73% live weight (Men et al unpublished). Under the described system production is very profitable, but under extensive conditions poaching poses an issue similar to hunting of migrating species. Knowledge related to the biology of some species such as Mexican duck is sufficient for its breeding, but for other species like frogs and invertebrates, basic biology is hardly known. Longer observation periods are required to evaluate the whole community and the productivity of each species.

Trade of some species may be easily promoted when traditional use is not lost, as in crayfish and whitefish, or recovered through trade organization as in vegetables. Other species such as ducks and frogs have a growing selective consumer market. Other local species just mentioned here should be evaluated. Multicultures allow harvesting and can therefore provide year-round employment.

Since irrigation and cropping procedures affect population dynamics, two management strategies may be adopted in irrigation ponds: The first option is allowing natural succession processes, in which natural (or artificial) ponds lead to a terrestrial community in about 20 years (De la Lanza and García 2002), thus reducing the effects of management. This strategy implies the programmed use of a number of ponds in several phases in order to harvest each species during its productivity climax. The second strategy implies periodical interruption of succession processes, and the return to initial phases, keeping some ponds on the more productive initial phases, while other ponds evolve to mature phases, less productive but with higher species diversity. The choice of a certain strategy depends on the current condition of each pond, besides the present and projected use by owners. Considering results, only the case of amphibians requires a management option difficult to achieve. All other experiments were successful from a bio-technical point of view. Efficient organization of harvesting processes may lead to sustainable production of these species, thus contributing to environmental conservation and employment generation under a new agro-ecological paradigm of natural resource management.

Final considerations

Native species production under semi-captivity in irrigation ponds was biologically, technically and economically feasible, in comparison to common carp monoculture. Most limiting factors can be overcome using appropriate management techniques.

The main premises for sustainable use of local wetland species stem from a strong producers organization; from legal and safety rights exerted upon the ponds and their water sources, and an institutional support to reactivate trading channels, besides promoting sustainable techniques among producers. Furthermore, the estimation of sustainable harvest and other sustainability indicators is needed in order to keep a reliable and continuous evaluation of the management system.

Acknowlwdgements

This study was supported by Universidad Autónoma del Estado de México (UAEM) and Consejo Nacional de Ciencia y Tecnología (CONACYT).

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